<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width,initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <div id="app"></div>
</body>
    <script src="https://unpkg.com/vue@next"></script>
    <script>
        const app = Vue.createApp({
               template:`
               <layout-demo>
                <template v-slot:header>
                    <h1>here might be a page title</h1>
                </template>
                <template v-slot:default>
                    <p>A paragraph for the main content.</p>
                    <p>and another one</p>
                </template>
                <template v-slot:footer>
                    <p>here's some contact info</p>
                </template>
              </layout-demo>
               `
            })
            app.component('layout-demo',{
                template:`
                <div class="container">
                    <header>
                        <sllot name="header"></slot>
                    </header>
                    <main>
                        <slot name="default"></slot>
                    </main>
                    <footer>
                        <slot name="footer"></slot>
                    </footer>
                </div>
                `
            })
            !              
           app.mount("#app");
    </script>
</html>